Re: [Emc-users] hal 'net' command puzzler

[Lars A. <la...@la...>]

My 2c trying to clear the fog.

For every signal in hal defined by one or more net statements: 

1) each line affecting "signal1" starts with "net signal1 "
2) exactly one term has to be an output
3) all other terms has to be inputs
4) all terms must be of the same variable type

Correct:
net s1 out1 in1 in2 in3
net s1 in4
net s1 in5 in6 

Incorrect:
net s1 out1 in1 in2 in3
net s1 out1 in4
net s1 out1 in5 in6

Repeat only the net name, not the output name.


> -----Original Message-----
> From: gene heskett [mailto:ghe...@wd...]
> Sent: den 5 maj 2012 14:47
> To: emc...@li...
> Subject: Re: [Emc-users] hal 'net' command puzzler
> 
> On Saturday, May 05, 2012 07:32:05 AM Andy Pugh did opine:
> 
> > On 5 May 2012, at 03:41, gene heskett <ghe...@wd...> wrote:
> > > arg[3], arg[4] arg[5] etc of a "net" commend can be repeated to add
> > > sending something from arg[2] to more than one load.  But I can't
> > > name a previously used output and send it to the 2nd place it needs
> > > to go.  Its s show stopper error.
> >
> > Argument order is not important except that the "signal" name is the
> one
> > directly after "net". Any HAL "signal" (the arbitrary name) can only
> be
> > netted to one output "driving" pin.
> >
> > So
> > net signal1 out1 in1 in2 in3
> 
> Which seems to say that the out1 name string in the first format,
> becomes
> the signal1 name string in the second format?
> 
> > net signal1 in4 in5 in6
> 
> Humm, in this latter case then we have a bunch of inputs only, so I'd
> have
> to assume that "signal1" would then be named as the out1 in the first
> format on a different line, effectively becoming a "driver pin"?
> 
> > Is probably the format you are looking for. There is no need for the
> > driver pin to be in the first net statement, incidentally.
> 
> Where the "driver pin" name is an arbitrary substitution of an "out1"
> named
> in the first format above?
> 
> In my present .hal, I have all the loadrt's at the top, and all the
> addf's
> next. Followed by the long list of setp's, then the net's are generally
> at
> the bottom of the list.
> 
> It occurs to me that the addf's using the servo-thread could
> potentially
> result in additional servo-thread sized delays if they are in the wrong
> order, and they are processed in the order given in the hal file.
> 
> Is that true?  In the html docs, under halshow at
> <http://www.linuxcnc.org/docs/devel/html/hal/halshow.html>
> the text quite a ways down the page uses "linksp" which I think has now
> been replaced with "net" for several years, but has the actual function
> description been changed such that they are not directly
> interchangeable?
> 
> But the net statements would seem to be more sensibly grouped under a
> function label, in the order of signal flow, in order to make the
> signal
> flow more obvious to us humans.
> 
> Am I on the right track?
> 
> Does linuxcnc have a utility that can scan a .hal file and draw a flow
> chart?  HalShow would appear to be similar, but demands a fully legal
> hal
> file so that linuxcnc can actually load up and run, so would seem to be
> of
> no use for troubleshooting a broken .hal.  And that is my instant
> problem.
> 
> I got nfs setup again on that machine last night late, so I can pull
> that
> hal file in and print it, killing trees is my most effective debugging
> tool
> it seems.  One could say I am using paper as a sub for my ever poorer
> short
> term memory. :(
> 
> Thanks Andy.
> 
> Cheers, Gene
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> My web page: <http://coyoteden.dyndns-free.com:85/gene>
> Support your right to arm bears!!
> 
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